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TotW June 1, 2012 — Working with e-mag PDFs

This weekend there will be two tips! This first tip is less about knitCompanion (although it is applicable), and more about working with PDFs that are very large in relation to the number of pages. This applies to any PDF where the photographs in the PDF are very high “dots per inch” and also any PDFs that are based off of professional print quality sources (such as e-mags).

So first let’s explore the PDF world. Most of the PDFs put out by designers are fairly normal in size in relation to the number of pages. Much of what controls the size of the PDF is the size/quality of the images inside the PDF. Most often this is a result of photographs, but other things can play into this as well. Overall, the measure of how much information (size of file) is needed is determined by the “dots per inch” used in images. For on screen viewing you don’t need much more than 150-200 dots per inch. Remember, all electronic displays are based on 72 dots per inch, and you want some extra so you can zoom without things getting blurry or grainy. However, if you are going to print an image professionally (say in a book or a glossy magazine) you need at least 600 dots per inch and many cameras take images of even higher quality (more dots per inch).

Most pattern PDFs are perfectly reasonable. Even if the photos are larger, there are not a lot of them. But, if you’ve worked with PDFs that are from e-books or e-mags where the provider took the original print layout and packaged it as a PDF without any image compression or size reduction you will notice that the PDF is VERY large in relationship to the number of pages. Anything that is more than 500k-1M/page probably falls into this category. So if you have a 5 page PDF and it is 5M, it probably has some very high quality images in it.

High quality images are great, but they can pose challenges for our mobile devices! Rendering these large images is tough for the mobile devices, and ultimately, all those “extra” dots per inch aren’t going to do you any good when you work with the file electronically. You will find that the PDFs may or may not open on your mobile device (depending on its horsepower) but working with them might be klutzy.

So now on to the tip, which is all about what to do about these REALLY BIG PDFs and make them easier to work with on your mobile device. Do not fear, it is pretty straight forward to “regenerate” these large PDFs into something more reasonable. You do need a computer, either windows or Mac will do.

For Windows:

Install the free Primo PDF system. (there are other systems, including Cute. And if you have full acrobat that will work to. I have to pick one to give instructions for tho).

Open the PDF you need to fix in acrobat reader, nitro (the reader that come with primo), etc.

Print it, but instead of printing to your printer, select Primo PDF as the printer. Now instead of a paper copy, you will get a new file.

The Primo print driver will kick off once you hit print and pop up a dialog box. It has several settings, you can select Screen, eBook, etc. I generally choose eBook or Screen for optimal use on my mobile devices. Continue on and name your new file.

Once its generated, compare the size of the new file to the original. It should be much smaller and should work much more efficiently in knitCompanion or any other app on your mobile device.

Mac:
Apple provides a built in PDF system called Quartz. Using Preview you can access this system, and use it to reduce the size of your PDFs. Please note the ability to access this functionality changes between Leopard and Lion and could continue to change as apple updates the Mac OS. Hearty thanks to mamajag for the written instructions below for both Leopard and Lion below.

You can use the quartz preset “reduce file size”. It will really shrink the file size, but the quality is not very good. Instead, followed the instructions at this link to create a new quartz filter that reduces the file size while remaining decent quality. Set the slider to about ¾ of full quality and get a good mix of quality/size.

If you have Lion, the new preset doesn’t show up until you have a copy in both the main Library>ColorSync>Presets folder and the main Library>PDF Services folders. Library is hidden by default, so if you need to get to it hold option and use the Go menu. Library should be an option then.

With Mac you may want to play around with the filters a bit. In some cases, I’ve found that the regeneration can make the colors of some photos wonky. Charts should still be ok, but you might lose some of the beautiful pictures.